Traditionally, a polymer material (such as a plastic material used to form key pad) can be marked by ink jet printing. In order to enhance the ink adhesion, Freon (e.g. chlorofluorocarbon (CFC)) is used to clean the surface of the polymer material prior to the printing process. However, the use of CFC is restricted or inhibited in the resent years because of environmental concerns. Laser marking technology which requires no CFC surface cleaning step and has advantages of easy operation and leading permanent marks has been widely applied in the plastic polymer industry to take the place of the ink jet printing technology.
The laser marking technology can be implemented by steps as follows: A light absorber or heat absorbers is firstly added in a polymeric material, and a laser beam is directed to the polymeric material. The surface of the polymeric material that subjected to the laser beam may be foam decomposed or/and carbonized to change the surface profiles and to make the dye involved in the polymeric material turning white, so as to form a mark on the surface of the polymeric material. Typically, carbon black can be added to change the color of the mark from white to black during the laser marking process. However, carbon black may cause the foaming decomposition occurring in the polymeric material reacting more violently, and the color of the mark may change to brown rather than black due to the violent foaming decomposition. Whereby, the mark formed on the surface of the polymeric material may be blurred and unidentified.
Therefore, a novel resin composition for laser marking and method for fabricating the same are desired for providing a laser mark having a more distinct profile and sharper contrast formed on the polymeric material.